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Rollup merge of rust-lang#125733 - compiler-errors:async-fn-assoc-ite…
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…m, r=fmease

Add lang items for `AsyncFn*`, `Future`, `AsyncFnKindHelper`'s associated types

Adds lang items for `AsyncFnOnce::Output`, `AsyncFnOnce::CallOnceFuture`, `AsyncFnMut::CallRefFuture`, and uses them in the new solver. I'm mostly interested in doing this to help accelerate uplifting the new trait solver into a separate crate.

The old solver is kind of spaghetti, so I haven't moved that to use these lang items (i.e. it still uses `item_name`-based comparisons).

update: Also adds lang items for `Future::Output` and `AsyncFnKindHelper::Upvars`.

cc `@lcnr`
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@fmease
fmease authored May 29, 2024
2 parents 5ab9868 + a03ba7f commit 1b0b2b3
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Showing 8 changed files with 40 additions and 62 deletions.
7 changes: 6 additions & 1 deletion compiler/rustc_hir/src/lang_items.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -228,13 +228,18 @@ language_item_table! {
AsyncFn, sym::async_fn, async_fn_trait, Target::Trait, GenericRequirement::Exact(1);
AsyncFnMut, sym::async_fn_mut, async_fn_mut_trait, Target::Trait, GenericRequirement::Exact(1);
AsyncFnOnce, sym::async_fn_once, async_fn_once_trait, Target::Trait, GenericRequirement::Exact(1);
AsyncFnKindHelper, sym::async_fn_kind_helper,async_fn_kind_helper, Target::Trait, GenericRequirement::Exact(1);
AsyncFnOnceOutput, sym::async_fn_once_output, async_fn_once_output, Target::AssocTy, GenericRequirement::Exact(1);
CallOnceFuture, sym::call_once_future, call_once_future, Target::AssocTy, GenericRequirement::Exact(1);
CallRefFuture, sym::call_ref_future, call_ref_future, Target::AssocTy, GenericRequirement::Exact(2);
AsyncFnKindHelper, sym::async_fn_kind_helper, async_fn_kind_helper, Target::Trait, GenericRequirement::Exact(1);
AsyncFnKindUpvars, sym::async_fn_kind_upvars, async_fn_kind_upvars, Target::AssocTy, GenericRequirement::Exact(5);

FnOnceOutput, sym::fn_once_output, fn_once_output, Target::AssocTy, GenericRequirement::None;

Iterator, sym::iterator, iterator_trait, Target::Trait, GenericRequirement::Exact(0);
FusedIterator, sym::fused_iterator, fused_iterator_trait, Target::Trait, GenericRequirement::Exact(0);
Future, sym::future_trait, future_trait, Target::Trait, GenericRequirement::Exact(0);
FutureOutput, sym::future_output, future_output, Target::AssocTy, GenericRequirement::Exact(0);
AsyncIterator, sym::async_iterator, async_iterator_trait, Target::Trait, GenericRequirement::Exact(0);

CoroutineState, sym::coroutine_state, coroutine_state, Target::Enum, GenericRequirement::None;
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_hir_analysis/src/collect.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1478,7 +1478,7 @@ pub fn suggest_impl_trait<'tcx>(
),
(
infcx.tcx.lang_items().future_trait(),
infcx.tcx.get_diagnostic_item(sym::FutureOutput),
infcx.tcx.lang_items().future_output(),
format_as_assoc,
),
(
Expand Down
6 changes: 5 additions & 1 deletion compiler/rustc_span/src/symbol.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -210,7 +210,6 @@ symbols! {
FsPermissions,
FusedIterator,
Future,
FutureOutput,
GlobalAlloc,
Hash,
HashMap,
Expand Down Expand Up @@ -439,8 +438,10 @@ symbols! {
async_fn,
async_fn_in_trait,
async_fn_kind_helper,
async_fn_kind_upvars,
async_fn_mut,
async_fn_once,
async_fn_once_output,
async_fn_track_caller,
async_fn_traits,
async_for_loop,
Expand Down Expand Up @@ -498,6 +499,8 @@ symbols! {
call,
call_mut,
call_once,
call_once_future,
call_ref_future,
caller_location,
capture_disjoint_fields,
catch_unwind,
Expand Down Expand Up @@ -911,6 +914,7 @@ symbols! {
fundamental,
fused_iterator,
future,
future_output,
future_trait,
gdb_script_file,
ge,
Expand Down
23 changes: 3 additions & 20 deletions compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,6 @@ use rustc_macros::{TypeFoldable, TypeVisitable};
use rustc_middle::bug;
use rustc_middle::traits::solve::Goal;
use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable, Upcast};
use rustc_span::sym;

use crate::solve::EvalCtxt;

Expand Down Expand Up @@ -454,12 +453,7 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_async_callable<'tc
.rebind(ty::TraitRef::new(tcx, future_trait_def_id, [sig.output()]))
.upcast(tcx),
];
let future_output_def_id = tcx
.associated_items(future_trait_def_id)
.filter_by_name_unhygienic(sym::Output)
.next()
.unwrap()
.def_id;
let future_output_def_id = tcx.require_lang_item(LangItem::FutureOutput, None);
let future_output_ty = Ty::new_projection(tcx, future_output_def_id, [sig.output()]);
Ok((
bound_sig.rebind(AsyncCallableRelevantTypes {
Expand Down Expand Up @@ -510,12 +504,7 @@ pub(in crate::solve) fn extract_tupled_inputs_and_output_from_async_callable<'tc
);
}

let future_output_def_id = tcx
.associated_items(future_trait_def_id)
.filter_by_name_unhygienic(sym::Output)
.next()
.unwrap()
.def_id;
let future_output_def_id = tcx.require_lang_item(LangItem::FutureOutput, None);
let future_output_ty = Ty::new_projection(tcx, future_output_def_id, [sig.output()]);
Ok((
bound_sig.rebind(AsyncCallableRelevantTypes {
Expand Down Expand Up @@ -592,13 +581,7 @@ fn coroutine_closure_to_ambiguous_coroutine<'tcx>(
args: ty::CoroutineClosureArgs<'tcx>,
sig: ty::CoroutineClosureSignature<'tcx>,
) -> Ty<'tcx> {
let async_fn_kind_trait_def_id = tcx.require_lang_item(LangItem::AsyncFnKindHelper, None);
let upvars_projection_def_id = tcx
.associated_items(async_fn_kind_trait_def_id)
.filter_by_name_unhygienic(sym::Upvars)
.next()
.unwrap()
.def_id;
let upvars_projection_def_id = tcx.require_lang_item(LangItem::AsyncFnKindUpvars, None);
let tupled_upvars_ty = Ty::new_projection(
tcx,
upvars_projection_def_id,
Expand Down
22 changes: 14 additions & 8 deletions compiler/rustc_trait_selection/src/solve/normalizes_to/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -407,16 +407,20 @@ impl<'tcx> assembly::GoalKind<'tcx> for NormalizesTo<'tcx> {
output_coroutine_ty,
coroutine_return_ty,
}| {
let (projection_term, term) = match tcx.item_name(goal.predicate.def_id()) {
sym::CallOnceFuture => (
let lang_items = tcx.lang_items();
let (projection_term, term) = if Some(goal.predicate.def_id())
== lang_items.call_once_future()
{
(
ty::AliasTerm::new(
tcx,
goal.predicate.def_id(),
[goal.predicate.self_ty(), tupled_inputs_ty],
),
output_coroutine_ty.into(),
),
sym::CallRefFuture => (
)
} else if Some(goal.predicate.def_id()) == lang_items.call_ref_future() {
(
ty::AliasTerm::new(
tcx,
goal.predicate.def_id(),
Expand All @@ -427,8 +431,9 @@ impl<'tcx> assembly::GoalKind<'tcx> for NormalizesTo<'tcx> {
],
),
output_coroutine_ty.into(),
),
sym::Output => (
)
} else if Some(goal.predicate.def_id()) == lang_items.async_fn_once_output() {
(
ty::AliasTerm::new(
tcx,
goal.predicate.def_id(),
Expand All @@ -438,8 +443,9 @@ impl<'tcx> assembly::GoalKind<'tcx> for NormalizesTo<'tcx> {
],
),
coroutine_return_ty.into(),
),
name => bug!("no such associated type: {name}"),
)
} else {
bug!("no such associated type in `AsyncFn*`: {:?}", goal.predicate.def_id())
};
ty::ProjectionPredicate { projection_term, term }
},
Expand Down
36 changes: 6 additions & 30 deletions compiler/rustc_trait_selection/src/traits/project.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1680,14 +1680,8 @@ fn confirm_closure_candidate<'cx, 'tcx>(
args.coroutine_captures_by_ref_ty(),
)
} else {
let async_fn_kind_trait_def_id =
tcx.require_lang_item(LangItem::AsyncFnKindHelper, None);
let upvars_projection_def_id = tcx
.associated_items(async_fn_kind_trait_def_id)
.filter_by_name_unhygienic(sym::Upvars)
.next()
.unwrap()
.def_id;
let upvars_projection_def_id =
tcx.require_lang_item(LangItem::AsyncFnKindUpvars, None);
let tupled_upvars_ty = Ty::new_projection(
tcx,
upvars_projection_def_id,
Expand Down Expand Up @@ -1816,14 +1810,8 @@ fn confirm_async_closure_candidate<'cx, 'tcx>(
args.coroutine_captures_by_ref_ty(),
)
} else {
let async_fn_kind_trait_def_id =
tcx.require_lang_item(LangItem::AsyncFnKindHelper, None);
let upvars_projection_def_id = tcx
.associated_items(async_fn_kind_trait_def_id)
.filter_by_name_unhygienic(sym::Upvars)
.next()
.unwrap()
.def_id;
let upvars_projection_def_id =
tcx.require_lang_item(LangItem::AsyncFnKindUpvars, None);
// When we don't know the closure kind (and therefore also the closure's upvars,
// which are computed at the same time), we must delay the computation of the
// generator's upvars. We do this using the `AsyncFnKindHelper`, which as a trait
Expand Down Expand Up @@ -1880,13 +1868,7 @@ fn confirm_async_closure_candidate<'cx, 'tcx>(
let term = match item_name {
sym::CallOnceFuture | sym::CallRefFuture => sig.output(),
sym::Output => {
let future_trait_def_id = tcx.require_lang_item(LangItem::Future, None);
let future_output_def_id = tcx
.associated_items(future_trait_def_id)
.filter_by_name_unhygienic(sym::Output)
.next()
.unwrap()
.def_id;
let future_output_def_id = tcx.require_lang_item(LangItem::FutureOutput, None);
Ty::new_projection(tcx, future_output_def_id, [sig.output()])
}
name => bug!("no such associated type: {name}"),
Expand Down Expand Up @@ -1919,13 +1901,7 @@ fn confirm_async_closure_candidate<'cx, 'tcx>(
let term = match item_name {
sym::CallOnceFuture | sym::CallRefFuture => sig.output(),
sym::Output => {
let future_trait_def_id = tcx.require_lang_item(LangItem::Future, None);
let future_output_def_id = tcx
.associated_items(future_trait_def_id)
.filter_by_name_unhygienic(sym::Output)
.next()
.unwrap()
.def_id;
let future_output_def_id = tcx.require_lang_item(LangItem::FutureOutput, None);
Ty::new_projection(tcx, future_output_def_id, [sig.output()])
}
name => bug!("no such associated type: {name}"),
Expand Down
2 changes: 1 addition & 1 deletion library/core/src/future/future.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,7 @@ use crate::task::{Context, Poll};
pub trait Future {
/// The type of value produced on completion.
#[stable(feature = "futures_api", since = "1.36.0")]
#[rustc_diagnostic_item = "FutureOutput"]
#[cfg_attr(not(bootstrap), lang = "future_output")]
type Output;

/// Attempt to resolve the future to a final value, registering
Expand Down
4 changes: 4 additions & 0 deletions library/core/src/ops/async_function.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@ pub trait AsyncFn<Args: Tuple>: AsyncFnMut<Args> {
pub trait AsyncFnMut<Args: Tuple>: AsyncFnOnce<Args> {
/// Future returned by [`AsyncFnMut::async_call_mut`] and [`AsyncFn::async_call`].
#[unstable(feature = "async_fn_traits", issue = "none")]
#[cfg_attr(not(bootstrap), lang = "call_ref_future")]
type CallRefFuture<'a>: Future<Output = Self::Output>
where
Self: 'a;
Expand All @@ -46,10 +47,12 @@ pub trait AsyncFnMut<Args: Tuple>: AsyncFnOnce<Args> {
pub trait AsyncFnOnce<Args: Tuple> {
/// Future returned by [`AsyncFnOnce::async_call_once`].
#[unstable(feature = "async_fn_traits", issue = "none")]
#[cfg_attr(not(bootstrap), lang = "call_once_future")]
type CallOnceFuture: Future<Output = Self::Output>;

/// Output type of the called closure's future.
#[unstable(feature = "async_fn_traits", issue = "none")]
#[cfg_attr(not(bootstrap), lang = "async_fn_once_output")]
type Output;

/// Call the [`AsyncFnOnce`], returning a future which may move out of the called closure.
Expand Down Expand Up @@ -143,6 +146,7 @@ mod internal_implementation_detail {
// `for<'env> fn() -> (&'env T, ...)`. This allows us to represent the binder
// of the closure's self-capture, and these upvar types will be instantiated with
// the `'closure_env` region provided to the associated type.
#[cfg_attr(not(bootstrap), lang = "async_fn_kind_upvars")]
type Upvars<'closure_env, Inputs, Upvars, BorrowedUpvarsAsFnPtr>;
}
}

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